80s Tarantulas

Specifically, as he may have looked in the cartoon, so it's a bit more simplified and animation-friendly.
Ninja Tarantulas

Contrary to the show, the toyline portrayed Tarantulas as a dull-witted ninja, so I went a little nuts with the idea. I was originally thinking he doesn't transform so much as he poofs into smoke and re-poofs as a spider (this IS supposed to be a weird parallel dimension Tarantulas, after all), although his limbs ended up looking like they could do a General Grievous-esque split to create 8 legs, maybe even using his kunai to complete the look.